An onomatopoeia meant to represent the noise a female (or perhaps a male) makes during the act of fellatio and takes in more than they can handle (deepthroating, in other words). It can be used in several tenses.

Male: "Baby if you keep sucking me like that I'm gonna take you to Red Lobster for cheddar biscuits"
Girl: *GARK GARK GARK GARK*